Soil microbiomes show consistent and predictable responses to extreme events

Increasing extreme climatic events threaten the functioning of terrestrial
ecosystems1,2. Because soil microbes govern key biogeochemical processes,
understanding their response to climate extremes is crucial in predicting the
consequences for ecosystem functioning3,4. Here we subjected soils from
30 grasslands across Europe to four contrasting extreme climatic events under
common controlled conditions (drought, flood, freezing and heat), and compared
the response of soil microbial communities and their functioning with those of
undisturbed soils. Soil microbiomes exhibited a small, but highly consistent and
phylogenetically conserved, response under the imposed extreme events. Heat
treatment most strongly impacted soil microbiomes, enhancing dormancy and
sporulation genes and decreasing metabolic versatility. Microbiome response to heat
in particular could be predicted by local climatic conditions and soil properties, with
soils that do not normally experience the extreme conditions being imposed being
most vulnerable. Our results suggest that soil microbiomes from different climates
share unified responses to extreme climatic events, but that predicting the extent of
community change may require knowledge of the local microbiome. These findings
advance our understanding of soil microbial responses to extreme events, and
provide a first step for making general predictions about the impact of extreme
climatic events on soil functioning.